layout: default title: "Model" permalink: /guide/model_mode/ parent: User Guide


When in Model mode, Scotty3D provides a polygon-based 3D modeler with basic subdivision capabilities. The central modeling paradigm is "box modeling", i.e., starting with a simple cube, you can add progressively more detail to produce interesting 3D shapes. You can also use subdivision to get smooth approximations of these shapes.

MeshEdit supports four basic actions on mesh elements (move, rotate, scale, and bevel), plus a collection of local and global mesh editing commands.

Note that MeshEdit (and more broadly, Scotty3D) will only operate on meshes that are manifold (i.e., the union of faces containing any given vertex v is a topological disk). Likewise, all mesh operations in Scotty3D will preserve the manifold property, i.e., manifold input will always get mapped to manifold output. This property is key for ensuring that many algorithms in Scotty3D are "well-behaved", and that it always produces nice output for other programs to use. If you load a mesh that is non-manifold, you can still use it in your scene and render with it, but editing will not be supported.

Editing Mesh Elements

In Model mode you can inspect mesh elements by left-clicking on vertices, edges, faces, and halfedges. Information about these elements will be shown in the left sidebar.

In this mode you can change the geometry (i.e., the shape) of the mesh by transforming mesh elements in the same way you can transform scene objects. Note that the transformation widget again has three modes of operation, which you can toggle through by pressing the r key.

selecting an edge

selecting an edge


The bevel action creates a new copy of the selected element that is inset and offset from the original element. Clicking and dragging on an element will perform a bevel; the horizontal motion of the cursor controls the amount by which the new element shrinks or expands relative to the original element, and the vertical motion of the cursor controls the amount by which the new element is offset (in the normal direction) from the original element. It is important to note that a new element will be created upon click even if no inset or offset is applied. Therefore, if you're not careful you may end up with duplicate elements that are not immediately visible. (To check, you can drag one of the vertices made.)

There are three possible types of bevels:

The following functions provide a bit more flexibility with how much to bevel the surface by: [Videos coming soon]

Local Connectivity Editing

In addition to beveling, a variety of commands can be used to alter the connectivity of the mesh (for instance, splitting or collapsing edges). These commands are applied by selecting a mesh element (in any mode) and pressing the appropriate key, as listed below. Local mesh editing operations include:

The following operations will have videos soon.

Global Mesh Processing

A number of commands can be used to create a more global change in the mesh (e.g., subdivision or simplification). These commands can be applied by pressing the appropriate sidebar button with a mesh selected. Note that in scenes with multiple meshes (e.g., those used by the path tracer), this command will be applied only to the selected mesh.

Key Bindings

Key Command
c Center the camera on the current element.
m Use the Move tool.
r Use the Rotate tool.
s Use the Scale tool.
b Use the Bevel tool.
v Select the current halfedge's vertex
e Select the current halfedge's edge
f Select the current halfedge's face
t Select the current halfedge's twin
n Select the current halfedge's next
h Select the current element's halfedge
delete Erase the currently selected vertex or edge.

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